Such ampules are manufactured by blow-molding in a mold comprising of two identical parts of mirror-image construction. Following completion of the blow-molding process, the two parts of the mold are separated from one another in a direction perpendicular to the plane of separation of the mold. Separation of the mold parts enables removal of the ampule from the mold. When several ampules are formed simultaneously, mold separation permits removal of the ampule block from the mold. Separation of the mold parts forms markings on the ampule, which markings define a longitudinal middle plane.
In a known ampule of this type (European Patent 0 326 391 A2 and U.S. Pat. No. 5,046,627 to Hansen, the subject matter of which is hereby incorporated by reference), two longitudinal venting passages are provided which lie in the inside wall of the ampule neck. During removal of the contents from the ampule by an injection member, the cone or conical member of the injection member is introduced into the ampule neck and engages the neck inside wall in a sealed manner. The longitudinal passages permit the inlet of air into the ampule, and are located in the longitudinal middle plane of the ampule.
In the case of this known ampule, erroneous functions of the longitudinal passages often occur due to improper formation. Either insufficient air can flow through the longitudinal passages to allow sufficiently rapid removal of the contents of the ampule, or the liquid in the ampule can leak out through the longitudinal passages, because the longitudinal passages may be manufactured without suitably uniform definition, and therefore, without the required tolerances.